Prostate brachytherapy, which implants radioactive seeds throughout the gland in order to kill cancerous tissue, is an increasingly popular method of treating localized prostate cancer. In the US, the number of implants increases by about 10% annually, and an estimated 50,000 to 60,000 procedures were performed in 2002. The five-year survival rate for prostate brachytherapy is comparable to the survival rate for radical prostatectomy. The placement of seeds is planned either in advance of treatment or in the operating room using dosimetry software that incorporates conventional ultrasonic images of the prostate and its surrounding anatomy. However, seeds often become displaced because of movement and distortion of the gland during seed insertion, and conventional ultrasonic imaging does not effectively show the actual location of implanted seeds. Consequently, some targeted regions may receive an insufficient dose. As a result, at least 15,000 procedures in the US provided inadequate dosage in 2002. An improved means of visualizing seeds would enable corrective seed placements to be performed and could result in marked improvement in treatment efficacy. The research proposed in this application seeks to develop novel advanced ultrasonic imaging methods that overcome the limitations of conventional ultrasonic instruments now used for imaging the prostate and implanted seeds. The proposed studies will investigate correlation, resonance, modified-elastographic methods applied alone and in combination, using tissue-mimicking phantoms, in vitro tissue specimens, animals and human subjects. If successful, the study will result in improved sensitivity and specificity in ultrasonic images of seeds. The proposed research will be performed collaboratively by engineers and scientists at Riverside Research Institute working with medical physicists and radiation oncologists at the New York Presbyterian Medical Center of Columbia University. Technical support in the form of consulting, software, seeds, etc., will be provided by Varian Medical Systems, Inc., which offers a potential path for translating the research results into a commercial product.